Back in September, John Kerry told Washington Democrats that America faced a “Munich moment” in deciding how to respond to Syria’s use of chemical weapons. He called Bashar al-Assad a “two-bit dictator” who would commit more atrocities unless he was stopped.

Right idea, wrong war. The real Munich moment of our times is taking place in Ukraine.

Vladimir Putin is on the march, and there’s no telling how far he’ll go if he’s allowed to gobble up Crimea without paying a serious price. That is the lesson of Munich, the infamous agreement in 1938 when Britain’s Neville Chamberlain struck a deal with Adolf Hitler that Chamberlain claimed would lead to “peace for our time.”

Virtually every president faces a Munich moment, usually more than one. It is a test of courage and wisdom over hope and rationalizations. More often than not, it involves Russia. From Stalin and Khrushchev in Soviet days to Putin now, the Bear is either asleep or ravenously hungry.

Now it is Barack Obama’s turn to face the test. Syria was a pop quiz, and we are about to see if he learned anything from his failure to lead after his “red line” pledge.

So far, his resolve remains an unanswered question. And that fits a troubling pattern.

Even as Russia invaded Georgia in 2008, Obama campaigned on the idea that the world automatically would be a better place when he replaced George W. Bush. It was a naïve and self-aggrandizing assumption, yet it was the basis of his “reset” approach to Russia.

Over several years, he could point to modest Russian cooperation on various fronts, but it came at too high a price. Some European allies believe he sacrificed their security to appease Putin.

Even during his re-election campaign in 2012, Obama mocked Mitt Romney’s observation that Russia remained our top geopolitical foe. And he blinked over Kerry’s ­“Munich moment” in Syria by letting Putin broker the deal that kept Assad in power in exchange for a promise to destroy his chemical weapons. The deal collapsed, and the slaughter continues.

Most important, Russia has been dragging its feet on Iran, giving the impression it wouldn’t mind if the mullahs got the bomb.

The invasion of Crimea should have removed any doubts about whether Russia could be trusted as a partner, yet Obama resisted recognizing the historic parallels. The president’s initial reaction was sleepy, his first public comments conveying a don’t-bother-me-with-distractions attitude. To underscore his indifference, he went to a partisan gab-fest before going on a golfing vacation.

In recent days, the lack of seriousness finally seems to be giving way to a realization that Obama faces a crisis of the first order. Yet what he will do, if anything, remains far from clear.

Part of the problem is that Western Europeans are assuming their usual quisling positions by resisting any meaningful financial and economic penalties. The scenario proves how corrosive the lack of American leadership can be to a stable world. Appeasement is contagious.

Meanwhile, the outcome of the referendum in Crimea is a foregone conclusion and sets the stage for Russian annexation. Obama and Kerry warn vaguely of “consequences,” but Putin is dismissive and seems more likely to extend his reach into eastern Ukraine than to back off. No wonder our allies in Eastern Europe, having lived under the Soviet yoke, are nervous.

They know the stakes. We will learn soon whether Obama does, for his Munich moment has arrived.

Andy’s real rival is…

A savvy friend sizes up New York politics this way: “Andrew Cuomo is running against Bill de Blasio.” He was only half joking.

Unless you’ve been on Mars, you know that Gov. Cuomo’s re-election campaign is off to an unorthodox start. He’s an overwhelming favorite to win a second term, but his early moves aim not to shore up his Democratic base as much as to appeal to those most likely to support a Republican opponent.

That’s where his fellow Dem de Blasio is coming in handy. The radical new mayor thinks voters gave him a blank check and insiders say he believes he can roll Albany and get anything he wants. He started by demanding approval of a tax hike on upper incomes to pay for pre-kindergarten expansion, while also trying to strangle the charter-school movement.

Both are terrible ideas — and tailor-made for a governor looking to show he’s no mad lib. Cuomo waited about 30 seconds before shooting down the tax plan, saying the state would fund pre-K, then waded into the charter battle by promising to save them. Both moves aim to give New Yorkers who are thinking of leaving reasons to stay.

The result is that de Blasio looks naïve and arrogant, while Cuomo looks both sensible and bold. He ought to pay de Blasio for that kind of image-making.

The truth is that Cuomo was always going to take a more prominent role in Gotham after Michael Bloomberg left City Hall. Bloomy had a giant footprint and didn’t let the governor get much traction in his town.

But de Blasio’s missteps are speeding up that transition and making Cuomo a go-to guy for those who think the mayor is from another planet. It will be fascinating to see how much political capital de Blasio wastes before realizing he’s being overmatched and outmaneuvered.

Teachers go for ‘broke’

News flash: With City Hall and the teachers union negotiating a new contract, union boss Michael Mulgrew asked for the sun and the moon, then promised, “We’re not trying to bankrupt the city.”

Whew — glad he cleared that up.

Dems do the ‘minimum’

An uninformed voter is a politician’s best friend, and here is more proof. When a national poll by Clarus Research asked about Democrats’ plan to raise the minimum wage to $10.10 over three years, a whopping 69 percent approved and only 29 percent opposed.

But later in the survey, pollsters added key information before asking about the topic again, saying: “A recent report by the Congressional Budget Office says that raising the minimum wage to $10.10 over the next three years would increase the incomes of 16.5 million Americans while eliminating 500,000 jobs. Does that trade-off seem acceptable or unacceptable to you?”

The answers flipped: Only 35 percent found the trade-off acceptable, while 57 percent said it wasn’t.

The contrasting responses illustrate that, when they have the facts, voters understand economist Milton Friedman’s line that “there is no such thing as a free lunch.”

If only the pols would stop pretending otherwise.

Credibility ‘Gap’ for prez

Knowing how single-minded the Secret Service is about protecting the president, it was astonishing that Obama ran into a Gap store in Midtown last Tuesday for a little shopping. Bet he wouldn’t try that in Chicago, where, to judge from the murder rate, half the customers would be packing heat.